If an area is congested that will change the average speed anyway, so the speed limit is irrelevant and reducing it will not help.If not congested then surely all you do is keep the traffic in the area for longer - would that not increase pollution?!

the rest of the suggestions:

Re-designing speed bumps to stop cars speeding up and slowing down between themRestrictions on engine idling during short stops such as outside schools and hospitalsMore charging points for electric cars in residential areasPlacing the most commonly-used rooms in new houses away from polluting roadsTraining drivers to be more fuel efficient by driving more smoothly

All the rest seem to be good suggestions - I like the fact that there is some lateral thinking in saying that house design could also help...and speed bumps redesign would be good - and smoother driving, well that is very much what we would support...

If an area is congested that will change the average speed anyway, so the speed limit is irrelevant and reducing it will not help.If not congested then surely all you do is keep the traffic in the area for longer - would that not increase pollution?!

I think the point is that speed humps are often put in 30mph zones to try and make people stick to 30. If instead you had a 20mph limit (with the expectation that people will then be closer to 30 than with a 30 limit, where they're often closer to 40) you achieve a better effect for air pollution.

Personally I think those that have been in favour of the humps should be personally footing the bills for taking them out. Bloody stupid ideas in the first place It's just going to result in another load of shonky patches that quickly disintegrate into more potholes

As part of the report of this and the increase in oil prices, an AA spokesman was quoted as saying that cars do 3 miles less to the gallon in winter. Now I thought engines were more efficient with cold air, so have I got it wrong, or is it because more ancillaries (lights, heating, heated screens/seats etc) are on?

angus wrote:As part of the report of this and the increase in oil prices, an AA spokesman was quoted as saying that cars do 3 miles less to the gallon in winter. Now I thought engines were more efficient with cold air, so have I got it wrong, or is it because more ancillaries (lights, heating, heated screens/seats etc) are on?

Going from summer to winter tyres on the Octy (and from 18" alloys to 16" steels) increased the MPG by about 10%. Maybe we should push manufacturers to stop fitting stupidly oversized wheels on their cars?

I suspect it's because many cars only do short runs, so in winter they don't warm up properly and perform at maximum efficiency. Diesels are particularly bad for this.

talking to a scooby owner at the petrol station the other day - he loves this weather - deep gulps of ice-cold air through the bonnet scoop = a more powerful car (not sure we touched on fuel efficiency )

Horse wrote:Re 20moh. It may be to do with keeping vehicles at constant speed, so reduced acceleration and braking.

possibly, on a course I recently had to do it was claimed that in one of the southern towns (I forget which one) where they introduced blanket 20mph limits, the average speed has actually increased and congestion is down...

Horse wrote:Re 20moh. It may be to do with keeping vehicles at constant speed, so reduced acceleration and braking.

possibly, on a course I recently had to do it was claimed that in one of the southern towns (I forget which one) where they introduced blanket 20mph limits, the average speed has actually increased and congestion is down...

Locals were opposed to the reduction - now fully support it...

Which average? Any mean is going to be horribly skewed by congestion at rush hour, and it's entirely believable a lower limit improves things there. But what about all the time stolen from road users in the quieter parts of the day?And congestion in surrounding areas? Overall traffic numbers (have people simply gone elsewhere? That only works until everywhere else is also just as bad, and we move to 10mph limits ).